They appear to have matched sugar for sugar between the diets, with the difference being that the processed diet had much more added sugar. Letting the partici

They appear to have matched sugar for sugar between the diets, with the difference being that the processed diet had much more added sugar. Letting the participants eat ad libitum was a deliberate part of the study design, which was intended to develop information about whether an ultra-processed diet encourages eating more in terms of food energy than an unprocessed diet does. I'd be curious to know how you would modify the study design to achieve that end while also eliminating ad libitum intake.